I presume this is the passage you're referring to:

    The problem is that I’m not getting much better at unprompted creative
    work. Observing problems and solving them, coming up with ideas and
    executing… those opportunities come few and far between in the university
    classroom. 

The problem is that writing is a total non sequitir of a answer to, "How can I get better at unprompted creative work?" There are lots of other things, from painting to programming to just going on walks that could make one better at unprompted creative work. So my question stands. Why writing? And why writing 500 words, specifically?